Abstract
Mutualisms ? cooperative interactions between species ? are central to the survival and reproduction of most organisms on earth. Despite their ubiquity, explaining the evolutionary persistence of mutualisms remains one of the greatest challenges for modern science. One problem is that mutualisms can be markedly dynamic: changes in biotic and abiotic conditions can tip the balance away from mutualistic exchange and towards antagonistic outcomes. Although scientists have developed approaches to test the short-term ecological responses of mutualisms to environmental changes, we lack the tools to predict the long-term evolutionary consequences of context changes. This is a crucial research avenue because under global change, mutualisms are evolving in rapidly changing environments. Global nutrient enrichment is of particular concern because increases in resource availability can drive shifts from mutualism to parasitism in the short-term, potentially favoring the evolution of aggressive, exploitative partner strategies. Using game theory modeling and a series of manipulative, multi-generational experiments, I will utilize the arbuscular mycorrhizal mutualism, arguably the world?s most abundant mutualism, responsible for massive global nutrient transfer, to ask: 1. Under what resource conditions are antagonistic strategies favored? 2. How does resource availability alter the evolution of cooperative strategies? 3. Do evolutionary changes reflect successful mutualist strategies? 4. Do changes in resource context alter host allocation patterns? I will exploit mycorrhizal root-organ cultures to experimentally evolve low- and high-quality fungal genotypes in varying resource conditions, characterization techniques to rank mutualist aggression and stable-isotope-probing to track the allocation of host resources to competing mutualists of varying quality. The evolutionary response of mutualistic partners to global change remain largely an open question. There is a critical need for research linking environmental changes with the evolutionary dynamics of these widespread partnerships. Can mutualisms adapt? My research will provide important insights into how resource availability alters the evolution of cooperation.
Netherlands